A common and inexpensive means of improving an automobile's performance is the addition of exhaust headers to the automobile's exhaust system. Exhaust headers improve performance of an automobile by reducing or eliminating backpressure from the exhaust system. When using exhaust headers, each cylinder in the automobile's motor emits exhaust through a separate cylinder exhaust pipe (instead of sharing an exhaust pipe with other cylinders, as is conventionally done). Each of these individual exhaust pipes lead into a collector, which in turn allows the exhaust to pass through an trailing exhaust pipe to the catalytic converter and muffler.
A common problem with high performance exhaust headers is the leakage of exhaust from the joint between the collector and the rest of the exhaust system (typically the joint is from the collector to the trailing exhaust pipe). This joint also acts as a reducer, as the diameter of the collector is typically larger than that of the rest of the exhaust system. This also increases pressure on the joint, as the exhaust is compressed in order to pass to the trailing exhaust pipe. It is common for this joint not to seal properly, thereby causing leakage. Furthermore, the seal on the joint is exposed to extremely high temperatures, frequent shaking, and movement of the engine within its mounts, further factors leading to the breakage of the seal and resultant leakage.
Flex type exhaust joints are commonly used in production vehicles. Stock production flex joints do not adapt well to use with high performance headers, as they tend to require high ground clearance, and do not provide for exhaust flow efficiency.
One attempt to provide a flexible joint is disclosed in U.S. Pat. No. 5,328,209 to Cromwell, entitled “Vehicle Exhaust Stack Joint Yieldable in All Directions”. Cromwell discloses a vertical joint, which is designed to pivot when the vertical exhaust pipe strikes a barrier such as a tree limb, and return to position when the barrier is passed. Such a joint fails to address the issues raised in performance header exhaust systems as it is designed to temporarily open (and thus leak) rather than maintain the exhaust pipe without leakage.
U.S. Pat. No. 6,931,843 to Gilli discloses an exhaust unit for engines, particularly for high performance vehicles. Gilli discloses a plurality of pipes (one from each cylinder) joined to a manifold having an equal number of pipes.
U.S. Pat. No. 3,063,741 to Bockerman discloses a yielding joint for exhaust pipes. Bockerman also discloses a joint for a vertical exhaust system designed to yield when the pipe strikes a barrier, such as a tree limb.
Other related art includes U.S. Pat. No. 5,683,119 to Emmons et al., disclosing a pipe joint and seal therefor, and U.S. Pat. No. 6,164,067 to Cronje, disclosing a knuckle joint for an exhaust system.